Cons: Fairly analytical sound, treble can be aggressive and unnatural, small soundstage

The HD25-1 has been my favorite (trans)portable headphone for quite a few months. I spend a few nights a week away from my home rig and the HD25 works wonders with my iBasso D10 and netbook. Hi-fi on the go has never been so rugged and simple. Best of all is their sonic versatility – though my backup portables, the AKG K181Dj, excel with certain genres and recordings, the Sennheisers perform more than adequately with anything I can throw at them.

Build Quality: When it comes to build quality, Sennheiser’s flagship portables can do no wrong. The structure of the HD25 is painfully elementary. They are neither flat-folding nor collapsible, with very simple rotating joints and removable metal hardware. The rough black plastic is resistant to cracks and scratches. A thick and sturdy steel cable, terminated in a beefy L-plug, completes the picture. The headphones are also very light and not likely to get damaged from falls. Lastly, every single part of the headphones is user-replaceable. From the detachable cabling to the headband padding to the cups and joints, the HD25 can be disassembled completely in just a few minutes.

Comfort: The HD25 is surprisingly light compared to headphones such as the AKG K181 and M-Audio Q40. The adjustable dual headband exerts very little pressure – the majority of the force is applied by the supraaural coupling. Though clamping force is fairly strong in the HD25, the structure does a great job of distributing it over the entire surface of the pads. The cups have a good range of motion despite lacking any joints whatsoever and conform very well to the shape of one’s head. Vinyl pads come installed on stock HD25s but some versions include the optional velour pads as well. Even if that isn’t the case, at $7+shipping the velour pads are a worthy investment, providing a comfort improvement at the expense of a tiny bit of isolation. Overall comfort falls just behind the likes of the impossibly light Senn PX100s and the circumaural CAL!.

Isolation: Though in general portable headphones can never isolate as well as IEMs, the HD25 can compete with certain shallow-insertion in-ears. While the vinyl pads isolate just a bit more than the velour ones, the tradeoff is unlikely to be worth it for most users. Even with the velour pads the isolation crown of the HD25-1 can be usurped only the hard-clamping AKGs and only if you’re lucky enough to get the AKGs to seal properly.

Sound: Upon first hearing the HD25-1 I was absolutely convinced that I would be giving them a perfect score in sound quality. Having owned them for a while, however, I can’t help but notice that for $200 headphones they are just slightly lacking here and there. But the fact that I am still using them as my primary portables is certainly telling of the fact that they are a competitive product. They are well-balanced, have good clarity and detail, and are quite transparent when it comes to sources. The bass is tight and accurate. It’s hard-hitting in character and more punchy than powerful as opposed to something like the K181Dj or M-Audio Q40. It has impressive extension, though it won’t keep up with the M-Audios down to the lowest reaches. It is also well-textured and does not bleed into the midrange. For a portable headphone the quantity of bass is just right – a bit more than what one would expect from an analytical headphone but far from AKG K81/K181 quantity.

The mids are neutral, clear, and detailed. Articulation is very good and sounds are well-separated. However, the HD25 is lacking noticeably in both soundstage width and depth, at least when compared to most full-size headphones. Most of the other closed portables I own don’t exactly shine in soundstaging either but I can’t help but be disappointed that the smaller and cheaper PX200-II has a more spacious sound. Sheer size aside, soundstage positioning is fairly precise and instrumental separation is excellent on all but the densest tracks. Towards the upper midrange the HD25-1 struggles to stay smooth and as a result is very unforgiving of sibilant tracks. The high end is quite present and reasonably extended but comes off a bit edgy and clinical at times. The overall sound, though, is quite pleasant and works particularly well for genres not dependent on soundstage size for the full experience. All of my quibbles aside, the HD25 is as good for use on the go as any portable headphone I have heard.

Value. (MSRP: $299.95; Street Price: $199) By far the most expensive headphone of the bunch, both in street price and MSRP, the HD25-1 is on another level in terms of balance and detail compared to all of the other featured portables. Compared, however, to full-size cans in the price range, as it sometimes is, the HD25 can come off as dull and rather compressed-sounding because of the narrow stage. The hard treble can also be a bit fatiguing for home use. But of course such comparisons are unfair precisely because I am not comfortable wearing my full-size cans outside while using the HD25 comes naturally. It is this versatility that makes the Sennheisers well-worth the $200 price tag and one of the easiest portable headphones to recommend.

This was a great review. I have had trouble finding the ideal pair of cans for almost 2 months now and after reading this I finally pulled the trigger. I've read a lot of reviews on here that are so technical and critical that I don't believe a common consumer like myself would necessarily pick up on half of that stuff; but you made it very sophisticated yet simple. I cannot wait for these to come in the mail as they will *wink, wink* be a tid bit better than my 6 year old Sennheiser PX100's. Again thanks!